High-tension current transformer



Patented Nov. 29, 1932 UNITED STATES PATENT OFFICE GEORG- KEINA'IH, OF BERLIN-CHARLOTTENBURG, AND JOSEPH SCHWEMMER, OF FAL- IKENSEE, GERMANY, ASSIGNORS TO SIEMENS & HALSKE, AKTIENGESELLSGHAIT, OF SIEMENSSTADT, NEAR BERLIN, GERMANY, A CORPORATION OF GERMANY HIGH-TENSION CURRENT TRANSFORMER Application filed March 14, 1929, Serial No. 346,847, and in Germany March 14, 1928.

Our invention relates to improvements in high-tension current transformers.

Our improved high-tension current transformer is distinguished by very small dimensions in comparison with the service voltage and is not only inexpensive itself, but is, furthermore, so designed that the plant in which it is installed is also less costly.

Apart from the air-cooled transformers, 0 the ordinary transformers consist in their external construction of an iron tank filled with a dielectric substance for the iron core and the windings and a bushing insulator dimensioned for the service voltage, which serves to introduce the high-tension primary leads into the grounded tank in a manner proof against flash-over and breakdown.

Extensive calculations and researches have shown that it is possible without increasing 0 the dimensions of the insulator determined by the flash-over voltage in air, to accommodate in the insulator, the transformer proper which in customary constructions is usually contained in a special metal tank, so 5 that the metal tank shrinks, so to say, into a simple base plate forming the bottom of the insulator. The height of the transformer is'thus considerably reduced in comparison with the ordinary designs. Hollow basesupported or spreader insulators (also known as pedestal insulators) already existing in the high-tension distribution plant may also be used for housing the electrical parts of the trans formers or a transformer according to our invention may be placed at a point at which otherwise a base-supported insulator would have to be provided.

It is furthermore possible to install a transformer subsequently and without any change 0 in the direction of the line by simplyreplacing the existing spreader insulator with another insulator in'the interior of which according .to ourinvention a transformer is housed.

It is also possible to design a bushing insection and half in elevation, a transformer f for outdoor use being assumed.

The hollow base-supported or spreader insulator i rests with its lower edge upon a packing ring (Z on the metallic supporting base I). This insulator may be a standard ar-' ticle of the usual size and shape (circular cross section). Within this insulator is housed a current transformer of any usual or suitable construction, for instance with annular iron core supported on the metal base or bottom 6 and a ring-shaped primary winding p threaded through the core at right angles. The secondary or low-tension winding e is directly wound upon the iron core 6, and is preferably covered with a protective envelope e" of solid insulating material, and terminates in terminals 70, which are arranged in an annular depression or countersunk portion of the bottom I). The risk of a flash-over from the high-tension parts to the low-tension winding is thus avoided and a reliable protection obtained against rain. The primary p is also preferably covered with a protective envelope, made of solid material insulating against high tension; in the drawing, the primary proper doesvnot really show, since the protective envelope encloses or covers the high-tension primary winding at all points thereof. The plane in which the high-tension winding is wound, extends in the direction of the longitudinal geometric axis of the insulator z, and the same remark will apply to the plane of the iron core e, both of said planes being axial changing their direction.

screwed into the dome-shaped cap a serving as protection against glow discharges and with reference to the insulator i, but perpendicular to each other. The height of the insulator i corresponds solely to the predetermined service voltage or operating voltage of the transformer, and the total or over-all height of the transformer, including its casing formed of the parts 0, a, i, b, is substantially the same as that of a customary base-supported insulator dimensioned for the same operating voltage. The height of taining'the terminals. In this chamber the level of the oil rises and falls as the temperature fluctuates, but in such a wa that the opening 0 remains covered at all tlmes. The high-tension conductors marked by the reference letter Z traverse the cavity it without One of them is for closing the cavity in an oil-tight manner, the other traverses the cap and is insulated in it, but both are in the interior of the cap connected to the extended ends or broughtout longitudinal leads f of the high-tension winding.

The insulator is in .the usual manner provided with ring-formed corrugations r to facilitate the running off of the rain.

When using two co-axially alined insulators joined by flanges at the lower ends and thus forming a buslnng insulator, the bottom is omitted and only anouter annular member remains. The current transformer is then preferably arranged symmetrically in the interior of the combined insulators.

secondary winding immersed in the oil, a

. metal'bottom fixed in an oil-tight manner at the foot of said insulator and adapted to sup port the iron core of said transformer, said metal bottom being countersunk along the edge to form an, annular cavity serving for bringing out the low-tension terminals, the high-tension connecting leads of theprimary wmding traversing said insulator longitudinally and being brought out at the top I said insulator.

2. A high-tension current transformer, comprising in combination, a hollow spreader oil insulator, an iron core with primaryand secondary winding immersed in the 011, a metal bottom fixed in an oil-tight manner at the foot of said insulator and adapted to support the iron core of said transformer, said metal bottom being countersunk along the edge to form an annular cavity serving for bringing out the low-tension terminals, the high-tension connecting leads of the primary winding traversing said insulator longitudinally and being brought out at the top, and a glow discharge protecting cap locate upon saidinsulator and enclosing the high-tension terminals and adapted to serve as oil expansion chamber.

3. The combination of a transformer com- 4 prising a high-tension primary, a core, and a low-tension secondary, with a casing enclosing said transformer and comprising anu per insulating member surrounding the hlg tension primary, and a metallic base member having a countersunk portion in the bottom of its outer surface, said low-tension secondary having terminals arranged in such countersunk portion.

4. A high-tension current transformer comprising a casing which includes a supporting bottom and a spreader insulator carried by such bottom and made eta-height corresponding solely to the "predetermined. operating voltage, an annular iron core within said casing, a low-tension winding on said I core, and a high-tension winding extending through the iron core and through sa1dlow tension winding, and located entirely within said insulator, the plane of said annular core, and the plane in which said high-tension winding is wound, both extending in the direction of the longitudinal axis of said insulator, and the ends of said high-tension winding leading to the outside at the top of 5. A high-tension current transformer comprising a casing which includes a supporting bottom and a spreader insulator carried by such bottom and made of a height corresponding solely. to the predetermined operating voltage,\an annular iron core within said casing, a low-tension winding, a hightension winding located entirely within said thereof, the height of said bottom being small relatively to the height of said insulator, an iron core located within the space bounded by said insulator and said bottom, a low-ten- 5 sion winding-and a high-tension winding, the

ends of the latter winding leading to the outside atthe top of said insulator, and an envelope enclosing the high-tension winding at all points thereof and made of solid material 1 insulating against high tension.

In testimony whereof we aflix our signatures.

GEORG KEINATH.

15 JOSEPH SGHWEMLIER. 

